This application is related to Japanese Patent Application No. Hei11(1999)-13293 filed on Jan. 21, 1999, whose priority is claimed under 35 USC xc2xa7119, the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a sheath flow cell and a blood analyzer using the same, more particularly to a sheath flow cell applicable to a sheath flow system and a multi-parameter blood analyzer using the same.
2. Description of Related Art
Flow cytometers utilizing a so-called sheath flow system are well known as apparatus for analyzing particles such as cells or blood cells in samples. In this system, a sheath liquid envelops and pinches a sample liquid (which contains particles) discharged from a nozzle so that the sample liquid flows thinly in a sheath flow cell, where optical measurement is carried out for counting and analyzing particles in the sample liquid. The term xe2x80x9csheath flowxe2x80x9d means a flow in which a flow of a floating particles-containing liquid is narrowed almost to the outer diameter of particles in the center of a sheath liquid which flows in a laminar-flow state within an orifice so that the particles are lined and passed in a row accurately. The sheath flow is utilized for analyzing various kinds of cells in a sample liquid of blood or the like prepared using a dye, a hemolytic agent, a reaction reagent and the like.
Such flow cytometers are desired to provide enhanced operating capability as well as more functions, but they have the disadvantage that measurement using the sheath flow cell and washing thereof take a lot of time. In order to improve the operating capability of flow cytometers, Japanese Unexamined Patent Publication No. Hei 2(1990)-176562 and PCT International Publication No. WO96/04542 disclose analyzers which have a multi-structure nozzle provided with a plurality of inlets for supplying sample liquids so that the sample liquids are introduced into a sheath flow cell via separate passages. The remaining sample liquids in a passage need not be washed away when switched from the one to another for measurement.
However, such a multi-structure nozzle is difficult to be manufactured and assembled and is expensive because of its complicated structure. Furthermore, the operating capability is not expected to improve so much because all the passages of the multiple nozzle must be washed finally after used.
In view of these circumstances, by studying the fluid characteristics of a flow cell having a simple structure, especially the relationship between flow velocity of a sheath liquid and flow rate of a sample liquid with respect to the configuration of a sheath flow cell, it has been found that the flow rate of the sample liquid can be at least doubled.
Accordingly, the present invention provides a sheath flow cell capable of providing an increased flow rate for sample liquids and a blood analyzer using the same to improve its operating capability.
The present invention provides a sheath flow cell comprising: a cell having a guide hole with an inlet thereto and an outlet therefrom for guiding a sheath liquid, the cell including a rectifying section, an accelerating section and an orifice section having a cylindrical through-hole, a cone-shaped through-hole tapered toward the outlet and a square prism-shaped through-hole, respectively, the cylindrical, cone-shaped and square prism-shaped through-holes serially and smoothly communicating to each other so as to define the guide hole; and a sample liquid supply nozzle having a cylindrical shape and extending from the inlet toward the accelerating section co-axially with the through-hole of the rectifying section, wherein the through-hole of the orifice section has a cross section having a side length of 0.1 mm to 0.4 mm and the through-hole of the rectifying section has an axial length four or more times greater than the inner diameter thereof.
The present invention further provides a blood analyzer comprising: a sheath flow cell as described above; a first supply section and a second supply section for supplying a sheath liquid to the inlet of the sheath flow cell and for supplying a blood-containing sample liquid to the sample liquid supply nozzle, respectively; a light source for irradiating the orifice section with light; a light-receiving section for receiving light emitted from the orifice section; and an analyzing section for analyzing a blood component in the sample liquid on the basis of optical information obtained from the light-receiving section.
These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.